Dielectrophoresis-assisted growth of metallic nanowires from an aqueous salt solution has been previously reported, but so far there has been no clear understanding of the process leading to such a bottom-up assembly. The present work, based on a series of experiments to grow metallic nano- and microwires by dielectrophoresis, provides a general theoretical description of the growth of such wires from an aqueous salt solution. Palladium nanowires and silver microwires have been grown between gold electrodes from their aqueous salt solution via dielectrophoresis. Silver microwire growth has been observed in situ using light microscopy. From these experiments, a basic model of dielectrophoresis-driven wire growth is developed. This model explains the dependence of the growth on the frequency and the local field enhancement at the electrode asperities. Such a process proves instrumental in the growth of metallic nanowires with controlled morphology and site specificity between the electrodes.